1. Field
Embodiments described herein relate to an electrical optical device, and more particularly, relate to a pixel circuit and a method of driving the pixel circuit.
2. Description of the Related Art
In recent years, display devices replacing CRT (Cathode Ray Tube) displays include organic EL devices that have self-emissive elements. For example, the organic EL device may be used as a backlight for a liquid crystal display (LCD) device or as an organic EL display device. In particular, the organic EL display device has attracted attention.
In the organic EL display device, a gray scale to be expressed is realized by controlling a driving transistor of each pixel circuit and the amount of current supplied to a light emitting diode thereof. If a characteristic of the driving transistor varies, the gray scale expression varies; hence, the quality of display is lowered.
To suppress influence of a variation in characteristic of a driving transistor on gray scale expression, a threshold voltage compensation technique is being developed which suppresses a variation in a threshold voltage (Vth) of a transistor.
A threshold voltage compensation circuit controls the amount of current to be supplied to a light emitting element using input image data, without depending on a variation in a threshold voltage of a driving transistor. Thus, it is possible to compensate for a variation in the threshold voltage of the driving transistor effectively and to improve uniformity of expression of the organic EL display device markedly. However, complexity and cross-talk remain issues in implementing threshold voltage compensation circuits.